Nice unit, looking good and bashy all together

One thing though, only the leftmost ogre has any brass on his gutplate and ironfist. I'd consider dropping the brass entirely and painting over his brass elements, or adding some brass to the plates / fists of the other bulls. Oddly enough, my ogres have boltgun + brass plates themselves ... But in your case I'd suggest dropping the brass entirely and redoing the first dude.
On your list, way to be original! Very cool as is, but could use to lose 2 leadbelchers and gain some hitty power. I would suggest pushing in 3 ironguts for the high strength beatings, and would be fun to model too, get to make your blue bulls but with extra smashiness. Here's my tweaks:
Bruiser - mawseeker, jade lion, great weapon = 178
4 Bulls - ironfists, standard, bellower = 190
4 Bulls - ironfists, standard, bellower = 190
3 Ironguts = 144
2 Leadbelchers - bellower = 120
Slave Giant = 175
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997 points
I like this a lot myself, could give it a try once I get some more stuff painted

GW on the bruiser makes him much scarier to knights or chariots or whatever, and dropping the armor is fine with the T6 on him. The guts are there to obliterate things and generally do your heavy lifting, and you really only need 1 unit of 2 belchers in 1000, to run up + shoot, then flee and rally/reload the next turn, then repeat.
- Salvage